Drive means for the cooling fan of an internal combustion engine

ABSTRACT

A hydraulic drive for the fan of an internal combustion engine in which an existing constant flow supply of hydraulic fluid is used to actuate a hydraulic motor to drive the fan. A

0 United States Patent [151 3,659,567

Murray [4 May 2, 1972 [54] DRIVE MEANS FOR THE COOLING FAN OF AN INTERNAL COMBUSTION [56] References Cited ENGINE UNITED STATES PATENTS Invenwfl Frederick Murray, Namwich. England 2,777,287 1/1957 Tweedale ..123/41.49 x Assigneez Rolls Royce Limited y England 1 Mayr l l [22] Filed: July 13, 1970 Primary Examiner-Al Lawrence Smith pp No: 54,123 Attorney-Cushman, Darby & Cushman [5 7] ABSTRACT Foreign Applicafiml Priority Data A hydraulic drive for the fan of an internal combustion engine in which an existing constant flow supply of hydraulic fluid is July 15, 1969 Great Britain ..35,551/69 used to actuate a hydraulic motor to drive the fan. A system of valves is provided to safeguard the operation of the primary [52] US. Cl ..l23/41.12, l23/4l.49 location ofuse ofthe hydraulic fluid [51] lnt.Cl ..F0lp7/02,F0lp 7/14,F0lp7/16 [58] Field of Search... ..l23/41.l1,4l.12,41.49 2Claims,3Drawing Figures r L I rti f '2 i l 24 I4 Pump L 25 I' L I Moror for Power Steering Mechanism Patented May 2, 1972 2 Sheets-Shoot l NOE floenlor if @516 66 Zjfmeem 4/7- .A/EYS Patented May 2, 1972 3,659,567

2. Sheets-Sheet 2 DRIVE MEANS FOR THE COOLING FAN OF AN INTERNAL COMBUSTION ENGINE This invention relates to drive means for the cooling fan of an internal combustion engine.

It has been a common expedient to drive the cooling fan of an internal combustion engine direct from the output or intermediate stage of the output of the engine itself. This is recognised to introduce various deficiencies. Thus, when the engine requires most cooling, normally at idling speed, the fan is turning at a slow speed and consequently cooling may be marginal; on the other hand when the engine is operating at high speed, although it requires relatively little cooling the fan is rotating at high speed and consequently absorbing an unnecessarily large amount of power.

Previous attempts to solve this problem have involved slipping clutches or similar devices to slow the fan at high engine speeds, or alternatively separate electrical drive means for the fan.

The present invention provides a way in which the fan may be driven hydraulically from what may be an already existing hydraulic power source.

According to the present invention drive means for the cooling fan of an internal combustion engine comprises a hydraulic pump adapted to be driven by the engine and to provide a substantially constant flow of hydraulic fluid, a primary duct adapted to convey the fluid to a primary location for use, a hydraulic fan motor connected to drive the fan, and a secondary duct adapted to convey the hydraulic fluid from the pump to the fan motor.

Preferably valve means are provided, adapted to regulate the flow of fluid to the motor in accordance with the temperature of the engine, thus these valve means may comprise bypass passage around the fan motor which is opened or closed in accordance with engine temperature.

In a particular instance, the primary location of use comprises the power steering mechanism of a vehicle which is propelled by the internal combustion engine.

The invention will now be particularly described, merely by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic view of a motor vehicle incorporating a cooling fan drive in accordance with the invention.

FIG. 2 is a diagram of the hydraulic circuit of the drive of the present invention, and

FIG. 3 shows the valving arrangement of the circuit of FIG. 2 in sectional view.

FIG. 1 shows a motor car which is propelled by an internal combustion engine 11 (shown in broken lines). The engine 11 is arranged to drive, by means not shown, a constant flow output hydraulic pump 12. It will be appreciated that although the pump is referred to as having a constant flow output, it will not in fact be precisely constant; but substantially constant over the normal speed range of the drive from the engine.

Output from the pump 12 is taken by hydraulic pipes and a valve system not shown in FIG. 1, to a first hydraulic motor 13 which actuates the power steering mechanism of the car, and to a second hydraulic motor 14 which drives the cooling fan of the engine.

FIG. 2 shows in more detail the hydraulic circuit of the drive for the motors 13 and 14. The output from the pump 12 passes through an output pipe 15, through a by-pass/relief valve 16, and by way of a pipe 17 to the fan motor 14. Fluid leaving the fan motor 14 exhausts through pipe 18 to the steering motor 13, and finally exhausts from there to return to the pump 12 via a pipe 21.

A by-pass passage 22 is provided which extends from the motor 13; to effect this a pipe 28 taps the pressure downstream of the motor 13 to the valve 25, while the pipes 26 and 22 act as pressure tappings for the upstream side of the motor 13.

In FIG. 3 the detailed construction of the valves 16 and 25 may be seen. The valve 16 comprises a body portion 30 within which operate a relief valve spool 31 and a thermostatically operated valve spool 32. The relief valve 31 is spring loaded by a compression spring 33 against a face of the body 30; it will be appreciated that should the back pressure across the fan motor 14 rise above a predetermined value, this pressure will overcome the spring pressure and allow flow through the by-passage.

The spool 32 seats against the upper extremity of a central hole through the spool 31, and is itself caused to take up an axial position in dependence upon the balance of forces between a compression spring 34 and a solenoid 35 operated by a signal which depends upon the temperature of the cooling fluid of the engine 11. Should the temperature of the engine fall below a predetermined value, the solenoid 35 will allow the spring 34 to push the spool 32 ofl the face of the spool 31 and to allow the hydraulic fluid to by-pass the motor 14, hence slowing or stopping the fan.

The valve 25 is provided to enable the steering motor 13 to take priority in the use of the output of the pump 12. Thus the valve 25 comprises a body 36 within which operates a piston 37, spring loaded by a compression spring 38. The piston is supplied, on opposite faces, with pressures from upstream and downstream of the motor 13 by way of the pipes 22 and 26 and the pipe 28 respectively. From the piston 37 is carried an obturating valve 39 which may open or close the further bypass passage 24. It is arranged that in the normal state of affairs, the pressure difference across the motor 13 and consequently across the piston 37 is such as to cause the valve 39 to close the by-pass passage 24 and consequently to enable the fan motor 14 to drive the fan (always provided that the bypass passage through the valve 16 is closed). Should a predetermined heavy demand be made upon the steering motor, the pressure across it will rise, consequently the valve 39 will open to open the by-pass passage 24 and allow the motor 13 to take the whole flow of the pump 12.

It will be appreciated that the system described allows the fan to be driven at substantially constant speed regardless of engine speed. The thermostatic valve enables the fan to be controlled in dependence upon the temperature of the coolant of the engine, while the relief valve ensures that should the fan motor seize, there will still be power available for the steering motor. Again, the valve 25 allows the steering motor to have priority over the fan motor for conditions where the steering motor is under load.

Various modifications could be made to the device described. Thus the fan could be driven from the output of a separate constant flow pump or by a pump adjusted for other uses. Again, the valve arrangement could well be altered. Also, the thermostat could be a wax thermostat arranged to drive the spool 32 direct.

Again it will be appreciated that the present invention enables the fan to be located remote from the engines, e.g., in front of the radiator matrix.

I claim:

1. Drive means for the cooling fan of an internal combustion engine of a vehicle having a power steering mechanism comprising a hydraulic pump having a substantially constant output flow of hydraulic fluid, a hydraulic motor having an inlet and outlet for driving said fan, a hydraulic motor having an inlet and outlet for said power steering mechanism, a first fluid duct connecting said output of said pump to said inlet of said fan motor, a second fluid duct connecting said outlet of said fan motor to said inlet of said motor for said steering mechanism, a third fluid duct connecting said outlet of said steering mechanisms motor to said hydraulic pump, a first bypass duct for conveying fluid from said first duct to said second duct, said first by-pass duct having valve means therein pressure at said outlet thereof by a predetermined value.

2. The drive means as claimed in claim 1 wherein said valve means in said first by-pass duct includes a first valve which is controlled by said temperature responsive control means and a second valve which opens said first by'pass duct when the back pressure across said fan motor exceeds a predetermined value.

l '0' I t Il 

1. Drive means for the cooling fan of an internal combustion engine of a vehicle having a power steering mechanism comprising a hydraulic pump having a substantially constant output flow of hydraulic fluid, a hydraulic motor having an inlet and outlet for driving said fan, a hydraulic motor having an inlet and outlet for said power steering mechanism, a first fluid duct connecting said output of said pump to said inlet of said fan motor, a second fluid duct connecting said outlet of said fan motor to said inlet of said motor for said steering mechanism, a third fluid duct connecting said outlet of said steering mechanism''s motor to said hydraulic pump, a first by-pass duct for conveying fluid from said first duct to said second duct, said first bypass duct having valve means therein including temperature responsive control means for opening said valve means when the temperature of the engine falls below a predetermined value, a second by-pass duct in fluid communication with said first duct and said second duct, said second by-pass duct having valve means therein including pressure responsive control means for opening said valve means of said second by-pass duct when the pressure at said inlet of said motor for said steering mechanism exceeds the pressure at said outlet thereof by a predetermined value.
 2. The drive means as claimed in claim 1 wherein said valve means in said first by-pass duct includes a first valve which is controlled by said temperature responsive control means and a second valve which opens said first by-pass duct when the back pressure across said fan motor exceeds a predetermined value. 